Backlash take-up device



Patented Oct. 17, 1950 2,525,945 BACKLASH TAKE-UP DEVICE Auguste LouisRicordel, Paris, France, assignor to Centre dEtudes Techniques etdInventions, Paris, France, acompany of France Application August 17,1945, Serial No. 610,888 In France September 25, 1941 Section 1, PublicLaw 690, August 8, 1946 Patent expires September 25, 1961 5 Claims. (01.74-409) For eliminating the detrimental effect of the slack in a drive,between the driving and the driven member, it is already known tomaintain the latter in contact with the motive surface of the drivingmember by means of a yielding pressure.

In the case of the drive of a helical wheel by an endless screw, or of anut by a screw spindle in particular, the yielding pressure exerted uponthe surface (opposed to that receiving the driving force) of the helicalteeth or of the screw thread is obtained by means of a second endlessscrew or a second nut driven by the first through the means of ayielding link.

This system has the drawback that it is complicated and will causecontinuous and important friction and wear. It could, however, renderservices in cases where the slack of the drive is continuously varying,as for instance, when the teeth or threads are not identical or when thewear is different from one tooth or thread to the other.

The object of the invention described below is a novel device for takingup the slack, particularly adapted for tooth and thread drives,especially for machines for cutting gears by means of member in order toremain in contact with the driven member and maintain contact at thedriving point, and is connected to the driving member by an adjustableconnection forming a vernier arrangement. i

By way of example, there are described below and shown on the joineddrawing two embodiments of said slack absorbing device applied to agear-cutting machine fitted with a. gear-wheel cutter.

Figures 1 to 3 refer to a dividing device drive by means of an endlessscrew and a helical wheel and show respectively: 1

Figure l a plan view, partially in section,

Figure 2, in diagrammatic section, an enlarged detail of the contacts ofthe driving endless screw and the endless screw used for taking up theslack with the helical wheel, and

Figure 3, in axial section, the enlarged. detail of the vernierconnection between both screws.

Figures 4 to 6 relate to the gear-wheel cutter carrying carriage driveby means of a screwspindle and corresponding nut, and are respectively:

Figure 4 a plan view, partially in section along the plane IVIV ofFigure 5,

Figure 5 a vertical section by the plane V-V of Figure 4, and

Figure 6 an enlarged diagrammatic section of the contacts of the drivingand the slack absorbing screws with the carriage.

According to Figures 1 to 3, the plate I2 carrying the crude to be cutinto a gear is integral with a helical wheel ll driven by an endlessscrew Ill. The slack absorbing member consists in another endless screw[5, also in mesh with the helical wheel I I and driven by the drivingendless screw I over the following adjustable connection: The drivingscrew 10 carries, at its end, a bevel pinion l3 meshing with a likebevel pinion l4 integral with a sleeve mounted freely upon the shaft ofthe slack absorbing endless screw I5. This sleeve, carrying the pinionI4, and the shaft carrying the endless screw l5 are coupled as follows:The sleeve is ended at the bottom by a toothed ring 11; the shaft of theendless screw [5 is integral with another toothed ring 18; between thetwo, and meshing with each of them, is a disc l6 toothed on both itssides. Upon tightening the nut 20, the pinion I4 is made integral withthe endless screw [5 and both endless screws ll] an IE will rotate atthe same speed.

For eliminating any slack in the drive, it is necessary, as seen inFigure 2, that the driving flanks of the threads of the endless screw inand the driving flanks of the threads ofthe endless screw [5 restagainst the opposedly directed flanks of the teeth of the helical wheelI I.

For obtaining this result, the parts l6-ll on one hand, and IBI8 0n theother, connecting the two screws to one another, carry a. large numberof teeth differing from one another by a very small amount, as forinstance 4|] and 4|, thus forming a sort of vernier permitting to adjustin rotation the position of screw l5 with respect to that of screw 10 ina very precise manner, and, consequently, to set up an exact contact ofscrew l5 and helical wheel H, Without any contact stress.

If, after having taken off the cap [9, the screw is maintained in itsposition by means of its end square 2! and the nut unscrewed, t eintermediate disc 16 fitted with the double 3 toothing may, after havingslightly lowered the sleeve of the toothed ring IS without freeing itfrom the shaft of screw l5, be rotated by one tooth, so that, when it isreset in mesh with the teeth I? of the sleeve carrying the bevel pinionM, the sleeve will have been rotated by of a revolution, corresponding,if the pitch of screws l and I is mm., to a slack absorption of 15X 1=0.009 mm.

threads of screw l5 will form, in operation, for

the teeth of wheel II, a stressless rest forcing said wheel to remain incontact with its driving screw I ll.

In the slack absorbing device of Figures 4 to 6 concerning a drive ofthe carriage carrying the gear-wheel cutter, by means of a screwspindle, it is seen that the carriage 24 forms a nut .23 on the drivingscrew spindle 22. The slack absorbing device consists in a second screwspindle 21 of the same but opposite pitch, driven in the oppositedirection by the two pinions and 26, and for which the carriage 2:; alsoforms a nut in 28. It is seen that, according to Figure 6, the slackwill be absorbed when, the driving screw 22 contacting with the rightside of thread 23, the control screw 21 will rest against the left side.The connection between the two screws comprises, as in the previousexample, a Vernier constituted by the disc 29 carrying on both its facesa large number of teeth, differing from one another by a small amountand adjustably meshing, on one hand, with teeth integral with the pinion26, and, on the other hand, with the teeth of the grooved sleeve 3|sliding upon the threaded spindle 2' with which it is integral inrotation.

The nut 32 screwed on the end of the screw spindle 27 fixes the threeparts of this Vernier connection to one another. If it is unscrewedwhile leaving the two drive pinions 25 and 26 in mesh, the Vernier disc29 may be rotated by one tooth and thereby the respective angularpositions of the screws 22 and 21 exactly adjusted for setting up exactcontact between the driving screw 22 and its nut 23 integral with thecarriage carrying the gear cutter.

Having now particularly described and ascertained the nature of my saidinvention and the manner in which it is to be carried into practice, Ideclare that what I claim is:

1. In a backlash take-up device, particularly for gear-cutting machinescomprising a driving worm, a driven element in mesh with said drivingworm and a slack absorbing worm engaging said driven element, fineadjustment means comprising a toothed crown rotatably mounted on theslack-absorbing worm, a gear-connection between the driving worm andsaid toothed crown, a second toothed crown slidably but not rotatablymounted on the slack: absorbing worm, a disc freely mounted on the slackabsorbi g worm, between the two toothed crowns, and having, on bothsides, teeth adapted to engage the teeth of the two crowns and difieringin number by only a very small amount, and means for axially pushing thesecond toothed crown and the disc so as to maintain said disc in meshwith the two crowns.

2. In a backlash take-up device, particularly for gear-cutting machinescomprising a driving worm, a driven element in mesh with said drivingworm and a slack absorbing worm engaging said driven element, fineadjustment means comprising a gear-wheel fixed on the driving worm, asleeve rotatably mounted on the slack absorbing worm, a secondgear-wheel fixed on said sleeve and in mesh with the gear-wheel of thedriving worm, a toothed crown fixed on the same sleeve, a second sleeveslidably but not rotatably mounted on the slack absorbing worm, a secondtoothed crown fixed on said second sleeve, a disc, between the twocrowns, freely mounted on the slack absorbing worm and having, on bothsides, teeth adapted to engage the teeth of the two crowns and differingin number by only a very small amount, and means for axially pushing thesecond toothed crown and the disc so as to maintain said disc in meshwith the two crowns.

, 3. In a backlash take-up device, particularly for gear-cuttingmachines comprising a driving worm, a driven element in mesh with saiddriving worm and a slack absorbing worm engaging said driven element,fine adjustment means comprising a gear-wheel fixed on the driving worm,a

sleeve rotatably mounted on the slack absorbing worm, a second,gear-wheel fixed on said sleeve and in mesh with the gear-wheel of thedriving worm, a toothed crown fixed on the same sleeve, second sleeveslidably but not rotatably mounted on the slack absorbing worm, a secondtoothed crown fixed on said second sleeve, a disc, between the twocrowns, freely mounted on the slackabsorbing worm and having, on bothsides, teeth adapted to engage the teeth of the two crowns and differingin number by only a very small amount, a thread on the slack absorbingworm, a nut screwed on said thread to squeeze the disc between the twotoothed crowns, and a square terminal head.

4. In a backlash take-up device, particularly for gear-cutting machinescomprising a driving worm, a helicoidal wheel in mesh with said drivingworm and a slack absorbing worm perpendicular to the driving worm andengaging the helicoidal wheel, fine adjustment means comprising abevel-wheel fixed on the driving worm,

- a sleeve rotatably mounted on the slack absorbing worm, a secondbevel-wheel fixed on one end of said sleeve and in mesh with the firstbevelwheel, a toothed crown fixed on the other end of this sleeve, asecond sleeve mounted on the slack absorbing worm and adapted to beaxially displaced thereon, a second toothed crown integral with saidsecond sleeve, a disc, between the two crowns, freelyv mounted on thesecond sleeve and having, on both sides, teeth adapted to engage the twotoothed crowns and differing in number by only a very small amount, athread on the slack absorbing worm, a nut screwed on said thread tosqueeze the disc between the two toothed crowns, and a square terminalhead.

5. In a backlash take-up device, particularly for gear-cutting machinescomprising a driving worm, a carriage provided with two threaded holes,the one meshing with said driving worm,

6 and a slack absorbing worm parallel with the driving worm and in meshwith the other threaded hole, fine adjustment means comprising aspur-gear fixed on the driving worm, a sleeve rotatably mounted on theslack absorbing worm, a second spur gear integral with said sleeve andin mesh with the spur-gear of the driving-worm, a toothed crown integralwith the same sleeve, a second sleeve fixed on the slack absorbing worm,a second toothed-crown integral with said second sleeve, a disc, betweenthe two crowns, freely mounted on the slack absorbing worm and having,on both sides, teeth adapted to engage the teeth of the two crowns anddifiering in number by only a very small amount, a thread on the slackabsorbing worm,

a nut screwed on said thread to squeeze the disc between the two toothedcrowns, and a square terminal head.

AUGUSTE LOUIS RICORDEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

